Diagnosis. A species with an obtusely pointed snout, apparently most closely related to A. dimidiata from which it differs as follows: (1) the dorsal scale rows are reduced to 15 before the 'vent; (2) there are only five upper labials; (3) lower ventral and subcaudal counts (at least in the female); (4) nasal entire; (5) black ventral coloration [BROADLEY 1971: 661]